This invention is related to the power generation industry and, more particularly, to the field of mounting frames supporting stator cores.
In the power generation industry, generator stator cores are supported on mounting frames. As is known in the art, generator stator cores generally include keybars positioned along an outer peripheral surface of the generator stator core. During operation of a power generation system, the generator stator core experiences an xe2x80x9coval modexe2x80x9d condition during which the generator stator core cyclicly deforms. The generator stator core temporarily deforms into an oval shape during operation. The deformations take place along both the horizontal and vertical axis. The xe2x80x9coval modexe2x80x9d condition experienced by the generator stator core accounts for some of the tangential and radial forces on a power generation system. Manufacturers of power generation systems are often faced with the problem of designing an efficient stator core frame support that can compensate for the xe2x80x9coval modexe2x80x9d condition experience by the generator stator core during operation. Current frame supports are very large and inefficient.
Power generation systems also experience transient faults during operation. When the power generation system experiences a transient fault, the generator stator core is suddenly displaced or rotated and it is difficult for a frame or frame support to sustain the forces associated with the transient fault. Manufacturers and users of high voltage generator stator cores often have great difficulty providing an efficient support for the generator stator core. In order to provide a frame support that is sufficient enough to sustain the forces associated with transient faults experienced during operation of the generator stator core, the frame support is normally very large and extremely inefficient.
Current power generation systems conventionally provide generator stator cores that have a higher tuned natural frequency. A generator stator core having a higher tuned natural frequency makes the power generation system more expensive and complex. A less stable power generation system requires a large core supporter that is also not cost effective and extremely inefficient.
Some generator stator core support frames incorporate an outer frame surrounding the core that is then attached to a bedplate or lower frame such as seen in U.S. Pat. No. 6,091,177 by Carbonell et al. titled xe2x80x9cSpring Mounting For An Electric Generator.xe2x80x9d The mounting frame surrounds the core and connects to all of the keybars positioned on the outer peripheral portions of the core. The surrounding frame is then attached to a lower frame using side and lower connecting members. The combination of these connecting members provides a support frame that is inefficient and cumbersome. Furthermore, the combination of the surrounding frame and the support frame provides a support apparatus with an increased load path, i.e., the load from transient faults and vibratory forces must travel an increased distance.
A similar arrangement for such an apparatus can be found in U.S. Pat. No. 4,891,540 by Cooper et al. titled xe2x80x9cGenerator Core Support System.xe2x80x9d This support system connects to the generator stator core around the outer periphery of the generator stator core where the keybars are positioned. Similarly, the support system provides a complex and inefficient connection between the generator stator core and the support frame. This rigid connection does not relieve lateral and tangential forces associated with transient faults. Accordingly, excess force from transient faults can cause damage to the generator stator core and frame if the core is not properly fastened to a frame support that can withstand these forces.
As understood by those skilled in the art, it is common to support a power generator stator core on a support frame that includes a connecting member between the generator stator core and the frame support in the six o""clock or twelve o""clock positions, i.e., a connecting member between the lower outer portion of the generator stator core and the stator core frame support. It is also common to support a power generator stator core on a support frame that includes a connecting member between the generator stator core and the frame support in the twelve o""clock position, i.e., a connecting member between an upper outer portion of the generator stator core and the stator core frame support. These configurations of frame supports provide inefficient connections that do not allow for the elimination of lateral forces associated with transient faults that occur during operation.
Additionally, it is costly and time consuming to provide support systems for power generators due to the cumbersome size and configuration of the current support frames necessary for accommodating transient faults and the oval mode experienced by power generation systems during operation. Some current support systems are so cumbersome that it is not possible to assemble the core and the core support system separate from one another. Presently, the core and the core support system must be constructed simultaneously. The simultaneous construction of the core and the support frame is extremely costly and time consuming.
In view of the foregoing, the present invention advantageously provides a high voltage power generation system including an apparatus for attaching a generator stator core to a frame support and methods of stabilizing a power generation system, reducing vibration and eliminating lateral movement of a generator stator core, low tuning the natural frequency of the generator stator core during operation, and compensating for an xe2x80x9coval modexe2x80x9d condition that occurs during operation of the power generation system that are efficient and cost effective. More particularly, the present invention advantageously utilizes spring supports to allow for a generator stator core to be supported by a generator stator core frame support in a manner that eliminates any rigid connections in the power generation system. The present invention also advantageously provides an apparatus and methods for protecting a power generation system from the forces associated with transient faults. The present invention further advantageously compensates for temporary deformations that result in radial and tangential forces that are encountered when the generator stator core experiences an xe2x80x9coval modexe2x80x9d condition during operation. The present invention still further advantageously compensates for the stresses applied to a power generation system associated with a generator stator core having a high tuned natural frequency by low tuning the natural frequency of the generator stator core.
More particularly, the present invention provides a power generation system that includes a stator core frame support member having a lower inner surface portion and a lower outer surface portion. The lower inner surface portion, for example, can have a substantially semi-annular shape. The lower outer surface portion is positioned to contact a support surface. The system also includes a generator stator core that can likewise have a substantially annular shape. The generator stator core preferably includes a plurality of keybars positioned spaced-apart and extending along the outer peripheral portions. The generator stator core is positioned to overlie the lower inner surface portion of the stator core frame support member and has a lower end portion positioned spaced-apart from and not in contact with bottom portions of the lower inner surface of the stator core frame support member. The upper end portion of the generator stator core is also positioned spaced-apart from and not in contact with the stator core frame support.
The system further includes a core supporter connected to the stator core frame support member. The core supporter is positioned to contact a plurality of keybars that are positioned along outer side peripheries of the generator stator core. The core supporter preferably has first and second core connecting means for attaching the stator core frame support member to the generator stator core. The core connecting means relieves vibration and prevents lateral movement of the generator stator core, low tunes the natural frequency of the generator stator core, and stabilizes the power generation system during operation to thereby provide a stator core frame support member that is efficient and cost effective. The first core connecting means preferably is connected to a first medial side outer peripheral portion of the generator stator core and the second core connecting means preferably is connected to a second medial side outer peripheral portion of the generator stator core. The second medial side outer peripheral portion of the generator stator core is positioned opposite the first medial side outer peripheral portion of the generator stator core. The first and second core connecting means are positioned substantially symmetrical along the longitudinal axis of the generator stator core. The combination of the first and second core connecting means connect portions of the stator core frame support member to portions of the generator stator core.
This configuration of a the generator stator core and the stator core frame support low tunes the natural frequency of the generator stator core and provides a more stable power generation system. This configuration also advantageously relieves vibration and prevents lateral movement of the generator stator core associated with transient faults that occur during operation. This configuration still further advantageously compensates for tangential and radial forces encountered by the power generation system when the generator stator core experiences the xe2x80x9coval modexe2x80x9d condition. By relieving vibration and eliminating lateral movement of the generator stator core and by further stabilizing the power generation system, a smaller and more efficient generator stator core frame support member is provided.
The present invention relieves vibration and prevents lateral movement of the generator stator core by providing a plurality of connections between the generator stator core and the stator core frame support member along medial side portions of the generator stator core and not bottom or top peripheries of the generator stator core. The power generation system is further stabilized by eliminating a support contact between a bottom portion of the generator stator core and the stator core frame support and by eliminating a support contact between a top portion of the generator stator core and the stator core frame support. These configurations of the power generation system advantageously eliminate lateral force components associated with transient faults, reduce vibratory forces associated with operation of the generator stator core, low tune the natural frequency of the generator stator core, stabilizes the power generation system, and further advantageously reduce costs and time associated with providing a support frame for a high voltage generator stator core. These configurations of the power generation system also advantageously compensate for temporary deformations of the power generation stator core when the generator stator core experiences an xe2x80x9coval modexe2x80x9d condition during operation.
The present invention still further provides a generator stator core support apparatus for relieving vibration and eliminating lateral movement of the generator stator core during operation, low tuning the natural frequency of the generator stator core, and stabilizing the power generation system. The generator stator core support apparatus preferably includes first core connecting means for connecting the generator stator core to a stator core frame support when the generator stator core is positioned to overlie lower inner surface portions of the stator core frame support. The first core connecting means preferably is positioned to contact a first outer peripheral medial side portion of the generator stator core and to contact a first upper medial side portion of the stator core frame support. The generator stator core support apparatus also includes second core connecting means for connecting the generator stator core to the stator core frame support. The second core connecting means preferably is positioned to contact a second outer peripheral medial side portion of the generator stator core. The second outer peripheral medial side portion is positioned opposite the first outer peripheral medial side portion of the generator stator core. The second core connecting means is further positioned to contact a second upper medial side portion of the stator core frame support. The second medial side portion of the stator core frame support is positioned opposite the first medial side portion of the stator core frame support.
The combination of the first and second core connecting means connects portions of the generator stator core to portions of the stator core frame support to thereby low tune the natural frequency of the generator stator core, stabilize the power generation system, relieve vibration, and prevent lateral movement of the generator stator core during operation. The combination of the first and second core connecting means is further positioned to support the generator stator core when connected thereto without a support contact between an upper or lower end portion of the generator stator core and the stator core frame support. There is no longer a stiff support between the generator stator core and the stator core frame support when the connecting support is eliminated between the lower end portion or the upper end portion of the generator stator core and the stator core frame support.
By providing an interstitial space between the upper and lower end portions of the generator stator core and the inner surface portions of the stator core frame support, lateral forces associated with transient faults that occur during operation of the generator stator core are eliminated. This interstitial space also relieves vibration of the generator stator core during operation and compensates for temporary deformations that produce tangential and radial forces encountered by the generator stator core when experiencing an xe2x80x9coval modexe2x80x9d condition during operation. By low tuning the natural frequency of the generator stator core, relieving vibration, eliminating lateral movement, stabilizing the power of generation system and compensating for the xe2x80x9coval modexe2x80x9d condition, the present invention advantageously decreases the load from the generator stator core to the stator core frame support. The decreased load allows for a smaller and more efficient stator core frame support. A smaller frame advantageously provides a shorter load path along which the load from the generator stator core to the stator core frame support must travel. This configuration further advantageously reduces costs and time associated with providing a support frame for a high voltage generator stator core thereby providing an efficient stator core frame support.
The present invention also provides a method of stabilizing a power generation system, relieving vibration, eliminating lateral movement and low tuning the natural frequency of the generator stator core during operation. The method includes the step of attaching a first core supporter which has a biasing support member that includes an elongate spring bar to a first upper medial side portion of a stator core frame support. The method also includes attaching a second core supporter which also has a biasing support member with an elongate spring bar to a second upper medial side portion of the stator core frame support. The second upper medial side portion is positioned opposite the first upper medial side portion so that the combination of the first and second core supporters are positioned substantially symmetrical along portions of the frame support. The method further advantageously includes positioning the generator stator core to overlie lower inner surface portions of the stator core frame support, connecting the generator stator core to the first core supporter along a first medial side portion of the generator stator core, and connecting the second core supporter to a second medial side portion of the generator stator core. The second medial side portion is preferably positioned opposite the first medial side portion of the generator stator core, and the combination of the connections between the first and second core supporters and the first and second medial side portions of the generator stator core form a connection between the generator stator core and the stator core frame support. The connection between the generator stator core and the stator core frame support advantageously reduces vibration and eliminates lateral forces experienced by the generator stator core, low tunes the natural frequency of the generator stator core, and provides stabilization to the power generation system during operation without a support contact between an upper or lower end portion of the generator stator core and the stator core frame support.
The method of stabilizing the power generation system provided by the present invention advantageously reduces the cost associated on constructing power generation systems. The method further advantageously reduces the time associated with constructing a frame support to low tune the natural frequency of the generator stator core and stabilize the power generation system. The method also advantageously eliminates lateral force components and vibration forces associated with transient faults during operation of the high voltage generator stator core. The method still further advantageously provides a stator core frame support that is efficient, cost effective, and can compensate for the vertical and horizontal force components associated with the xe2x80x9coval modexe2x80x9d condition experienced by the generator stator core during operation. The method also advantageously decreases the path along which a load must travel between the generator stator core and the stator core frame support.